content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.basetypes;
  
  import io.reactivex.rxjava3.operators.QueueSubscription;
  
  /**
   * Base class for empty, async-fuseable intermediate operators.
   */
  abstract class BasicEmptyQueueSubscription implements QueueSubscription<Void> {
  
      @Override
      public final boolean offer(Void e) {
          throw new UnsupportedOperationException("Should not be called!");
      }
  
      @Override
      public final boolean offer(Void v1, Void v2) {
          throw new UnsupportedOperationException("Should not be called!");
      }
  
      @Override
      public final void clear() {
          // no-op
      }
  
      @Override
      public final boolean isEmpty() {
          return true;
      }
  
      @Override
      public final Void poll() throws Exception {
          return null;
      }
  
      @Override
      public void request(long n) {
          // no-op
      }
  
      @Override
      public final int requestFusion(int mode) {
          return mode & ASYNC;
      }
  }